Astronomy

Kepler’s Laws

Johannes Kepler published three laws of planetary motion, the first two in 1609 and the third in 1619. The laws were made possible by planetary data of unprecedented accuracy collected by Tycho Brahe. The laws were both a radical departure from the astronomical prejudices of the time and profound tools for predicting planetary motion with …

Dark energy

Dark Energy is a hypothetical form of energy that exerts a negative, repulsive pressure, behaving like the opposite of gravity. It has been hypothesised to account for the observational properties of distant type Ia supernovae, which show the universe going through an accelerated period of expansion. Like Dark Matter, Dark Energy is not directly observed, …

The Universe

The Universe is defined as everything that physically exists: the entirety of space and time, all forms of matter, energy and momentum, and the physical laws and constants that govern them. However, the term Universe may be used in slightly different contextual senses, denoting such concepts as the cosmos, the world or Nature. Current interpretations of astronomical observations indicate that the age of …